This invention relates generally to drilling tools, and in particular to a tool for removing a broken portion of a tubular pipe fitting from a threaded bore.
Threaded junctions for attaching sections of tubular conduit to other components of a fluid system or machine are periodically subject to break. An example is a tubular fitting used for attaching a pipe that extends between an automotive engine intake manifold and a heater. That type of fitting has an end portion that is externally threaded for interfacing with an internally threaded opening in the manifold, thereby providing reliable attachment that may be rapidly connected and disconnected. Unfortunately, the fitting is prone to crack when subject to high torque or force, especially if the fitting has received many cyclic loadings. Typically when a fitting breaks, the externally threaded end portion separates from the remainder of the fitting and remains lodged within the opening of the manifold.
The broken portion of the fitting must be removed from the opening and a new fitting installed before the engine can be returned to normal operation. Unfortunately, the fitting and manifold are frequently positioned at a location having tight space constraints, making accessibility very difficult. To gain better access to the manifold, it can be necessary to disassemble parts of the engine or to remove the entire manifold. These steps take a substantial amount of time, and in view of the increased costs of automotive repair, are expensive. Further, there is no location on the broken fitting where a tool can readily engage the fitting to apply a torque that is strong enough to rotatingly remove it, especially so when the fitting is corroded within the manifold. A person can find it necessary to use a chisel or hacksaw to remove the broken fitting. These tools easily cause damage to the manifold.
Another alternative to remove the broken portion of the fitting is to grind it out using a conventional grinding tool with a powered drill. However, grinding increases the likelihood that the bore of the manifold will be damaged. Further, many tools of this type are too long, especially when the tool is combined with a drill, to permit alignment of the tool with the fitting for insertion unless the manifold is removed from the engine. If the grinding tool is not properly aligned, it may damage the structure of the manifold.
Among the several objects and features of the present invention may be noted the provision of a tool and process to remove a tubular member from a threaded bore; the provision of such a tool that operates in tight or confined space constraints; the provision of such a tool that permits removal of the tubular member without damaging the bore; the provision of such a method that removes a tubular member in a short period of time; the provision of such a tool that is economical; and the provision of such a tool that is easy to use.
A tool of the present invention removes a tubular member having a threaded exterior, such as a pipe fitting, from a threaded bore. The tool comprises a pilot section located at a front end of the tool for guiding the tool into an interior of the tubular member, the pilot having a cylindric shape along a longitudinal axis. A shank section is located at a back end of the tool and adapted for connection to a drill chuck, the shank section being aligned along the longitudinal axis. A central body engages the tubular member, the central body being located between the pilot section and the shank section, aligned along the longitudinal axis, and having a cross section transverse the longitudinal axis that is generally circular and that tapers in diameter from the shank section toward the pilot section along an entire length of the central body. At least one flute extends along a helical path on an exterior surface of the central body, the flute defining a cutting surface on the central body for cutting into the tubular member. The pilot section is adapted to guide the central body into the interior of the tubular member without the pilot section cutting into the tubular member, and the central body as disposed in the tubular member may grind away the tubular member without damaging the threaded bore.
In another aspect, a method of the present invention removes a tubular member having a threaded exterior, such as a pipe fitting, from a threaded bore. The method uses a tool having a longitudinal axis, a pilot section located at a front end of the tool, a shank section located at a back end of the tool, a central body located between the pilot section and the shank section and having a cross section transverse the longitudinal axis that is generally circular and that tapers from a narrowest diameter to a widest diameter along an entire length of the central body. The widest diameter is approximately equal to an inside diameter of the threaded bore. At least one flute extends along a helical path on the central body. The method comprises the steps of aligning the longitudinal axis of the tool with the tubular member and inserting the pilot section of the tool into an interior of the tubular member, thereby guiding the tool. An external surface of the central body is engaged against the interior of the tubular member. The tool is rotated at high speed whereby the flute grinds away the tubular member and does not grind away threads of the threaded bore for removing the tubular member without damaging the bore.
Other objects and features of the present invention will be in part apparent and in part pointed out hereinafter.